Techniques for extinguishing a display section under specific conditions have hitherto been proposed to save power of a portable device.
JP H10-051953 A discloses extinguishing a display section when a device is inoperative in order to save power of a main body of a device.
JP 2985200 B mentions extinguishing a display section at the time of recording or reproducing operation.
JP 4522526 B mentions that a display section is extinguished when an operation switch is locked by means of a hold function.
JP 3179256 U mentions a technique, though it is not a technique pertaining to extinction of a display section, of using a smartphone as a display device and a touch control terminal of a car audio system and controlling the car audio system by means of the smartphone through a wireless communication.
According to JP H10-051953 A, the display section stays lit up at all times when the recording/reproducing apparatus is in operation, which hence raises a problem of a poor power-saving effect being yielded during operation of the recording/reproducing apparatus.
According to JP 2985200 B, the display section is shut off even in the middle of recording or reproducing operation. Hence, a great power-saving effect is achieved during operation. In the meantime, there arises a problem of difficulty being encountered in ascertaining an operating status during operation after extinction of the display section.
As stated in JP 4522526 B, a conceivable way is to display time information for a predetermined period by operation of a switch. However, repeated illumination and extinction of the display section of the display section will cause erroneous operation or faulty operation as well as noise.